Snap Judgment #25: Chickensaurus Rex

#732: The chicken is the closest living relative of Tyrannosaurus Rex.

Let's open with a real quick reason why this falls under "probably" true: It is hard to define what "closest" relative means because the criteria is varied and different researchers/people may put different weight on different aspects. Genetically speaking, they do seem to be the closest, so let's take a look at some of the sources behind this claim!

In 2003 Mary Schweitzer, a paleontologist at North Carolina State University and the North Carolina Museum of Natural Sciences, along with a team of researchers, analyzed a 68 million-year-old T-rex leg bone discovered earlier that year. It was in remarkable condition and contained "a matrix of collagen fibers," which allowed them gain new insight into the terrifying and powerful T-Rex.

"The analysis shows that T-rex collagen makeup is almost identical to that of a modern chicken - this corroborates a huge body of evidence from the fossil record that demonstrates birds are descended from meat-eating dinosaurs," said Angela Milner, the associate keeper of palaeontology at the Natural History Museum in London. "So, it is very satisfying that the molecules have provided a positive test for the morphology."

The analysis was then used to compare the T-Rex bone's proteins with those of known animals. Simply put, out of 7 sequences, 3 matched chickens "directly." There we also matches with newts and frogs. It is important to note that there is a popular theory that alligators and/or crocodiles are close relatives, but we do not have every species in the database that was used (including alligators and crocodiles), so they may still prove an equal or even more accurate match. The Independentdiscusses this a bit more, but they seem to pretty much dismiss the connection to alligators without a very good reason, so i'd trust The Guardian (and the cited articles/journals, of course) over it.